This patch adds a generic next header compression layer interface. There
exists various methods to do a header compression after 6LoWPAN header
to save payload. This introduce a generic nhc header which allow a
simple adding of a new header compression format instead of a static
implementation inside the 6LoWPAN header compression and uncompression
function.
Signed-off-by: Alexander Aring <alex.aring@xxxxxxxxx>
---
net/6lowpan/Makefile | 1 +
net/6lowpan/nhc/Makefile | 3 +
net/6lowpan/nhc/core.c | 180 +++++++++++++++++++++++++++++++++++++++++++++++
net/6lowpan/nhc/core.h | 122 ++++++++++++++++++++++++++++++++
4 files changed, 306 insertions(+)
create mode 100644 net/6lowpan/nhc/Makefile
create mode 100644 net/6lowpan/nhc/core.c
create mode 100644 net/6lowpan/nhc/core.h
diff --git a/net/6lowpan/Makefile b/net/6lowpan/Makefile
index 415886b..d23d569 100644
--- a/net/6lowpan/Makefile
+++ b/net/6lowpan/Makefile
@@ -1,3 +1,4 @@
obj-$(CONFIG_6LOWPAN) := 6lowpan.o
+obj-$(CONFIG_6LOWPAN) += nhc/
6lowpan-y := iphc.o
diff --git a/net/6lowpan/nhc/Makefile b/net/6lowpan/nhc/Makefile
new file mode 100644
index 0000000..5fe76e47
--- /dev/null
+++ b/net/6lowpan/nhc/Makefile
@@ -0,0 +1,3 @@
+obj-$(CONFIG_6LOWPAN) += nhc.o
+
+nhc-y := core.o
diff --git a/net/6lowpan/nhc/core.c b/net/6lowpan/nhc/core.c
new file mode 100644
index 0000000..0bf103d
--- /dev/null
+++ b/net/6lowpan/nhc/core.c
@@ -0,0 +1,180 @@
+/* 6LoWPAN next header compression
+ *
+ *
+ * Authors:
+ * Alexander Aring <aar@xxxxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/netdevice.h>
+
+#include <net/ipv6.h>
+
+#include "core.h"
+
+static struct rb_root rb_root = RB_ROOT;
+static struct lowpan_nhc *lowpan_nexthdr_nhcs[NEXTHDR_MAX];
+
+static int lowpan_insert_nhc(struct lowpan_nhc *nhc)
+{
+ struct rb_node **new = &rb_root.rb_node, *parent = NULL;
+
+ /* Figure out where to put new node */
+ while (*new) {
+ struct lowpan_nhc *this = container_of(*new, struct lowpan_nhc,
+ node);
+ int result, len_dif, len;
+
+ len_dif = nhc->idlen - this->idlen;
+
+ if (nhc->idlen < this->idlen)
+ len = nhc->idlen;
+ else
+ len = this->idlen;
+
+ result = memcmp(nhc->id, this->id, len);
+ if (!result)
+ result = len_dif;
+
+ parent = *new;
+ if (result < 0)
+ new = &((*new)->rb_left);
+ else if (result > 0)
+ new = &((*new)->rb_right);
+ else
+ return -EEXIST;
+ }
+
+ /* Add new node and rebalance tree. */
+ rb_link_node(&nhc->node, parent, new);
+ rb_insert_color(&nhc->node, &rb_root);
+
+ return 0;
+}
+
+static void lowpan_remove_nhc(struct lowpan_nhc *nhc)
+{
+ rb_erase(&nhc->node, &rb_root);
+}
+
+struct lowpan_nhc *lowpan_search_nhc_by_nhcid(const struct sk_buff *skb)
+{
+ struct rb_node *node = rb_root.rb_node;
+ const u8 *nhcid_skb_ptr = skb->data;
+
+ while (node) {
+ struct lowpan_nhc *nhc = container_of(node, struct lowpan_nhc,
+ node);
+ u8 nhcid_skb_ptr_masked[nhc->idlen];
+ int result, i;
+
+ if (nhcid_skb_ptr + nhc->idlen > skb->data + skb->len)
+ return NULL;
+
+ /* copy and mask afterwards the nhid value from skb */
+ memcpy(nhcid_skb_ptr_masked, nhcid_skb_ptr, nhc->idlen);
+ for (i = 0; i < nhc->idlen; i++)
+ nhcid_skb_ptr_masked[i] &= nhc->idmask[i];
+
+ result = memcmp(nhcid_skb_ptr_masked, nhc->id, nhc->idlen);
+
+ if (result < 0)
+ node = node->rb_left;
+ else if (result > 0)
+ node = node->rb_right;
+ else
+ return nhc;
+ }
+
+ return NULL;
+}
+EXPORT_SYMBOL(lowpan_search_nhc_by_nhcid);
+
+struct lowpan_nhc *lowpan_search_nhc_by_nexthdr(const u8 nexthdr)
+{
+ return lowpan_nexthdr_nhcs[nexthdr];
+}
+EXPORT_SYMBOL(lowpan_search_nhc_by_nexthdr);
+
+int lowpan_nhc_do_compression(struct lowpan_nhc *nhc, struct sk_buff *skb,
+ u8 **hc_ptr, u8 *iphc0)
+{
+ int ret = 0;
+
+ if (!nhc)
+ return 0;
+
+ ret = nhc->compress(skb, hc_ptr);
+ if (!ret)
+ *iphc0 |= LOWPAN_IPHC_NH_C;
+ else if (ret == -ENOTSUPP)
+ return 0;
+
+ return ret;
+}
+EXPORT_SYMBOL(lowpan_nhc_do_compression);
+
+int lowpan_nhc_do_uncompression(struct sk_buff **skb, struct ipv6hdr *hdr)
+{
+ struct lowpan_nhc *nhc;
+ int ret = 0;
+
+ nhc = lowpan_search_nhc_by_nhcid(*skb);
+ if (nhc) {
+ ret = nhc->uncompress(skb);
+ if (!ret) {
+ skb_reset_transport_header(*skb);
+ hdr->nexthdr = nhc->nexthdr;
+ } else if (ret == -ENOTSUPP) {
+ net_warn_ratelimited("%s received %s which is not supported.\n",
+ (*skb)->dev->name, nhc->name);
+ }
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL(lowpan_nhc_do_uncompression);
+
+int lowpan_add_nhc(struct lowpan_nhc *nhc)
+{
+ int ret = -ENOMEM;
+
+ if (!nhc->uncompress || !nhc->idlen || !nhc->idsetup || !nhc->compress)
+ return -EINVAL;
+
+ nhc->idsetup(nhc);
+
+ if (lowpan_nexthdr_nhcs[nhc->nexthdr])
+ return -EEXIST;
+
+ ret = lowpan_insert_nhc(nhc);
+ if (ret < 0)
+ goto out;
+
+ lowpan_nexthdr_nhcs[nhc->nexthdr] = nhc;
+out:
+ return ret;
+}
+EXPORT_SYMBOL(lowpan_add_nhc);
+
+void lowpan_del_nhc(struct lowpan_nhc *nhc)
+{
+ lowpan_remove_nhc(nhc);
+ lowpan_nexthdr_nhcs[nhc->nexthdr] = NULL;
+
+ synchronize_net();
+}
+EXPORT_SYMBOL(lowpan_del_nhc);
+
+int lowpan_init_nhc(void)
+{
+ return 0;
+}
+
+void lowpan_cleanup_nhc(void)
+{
+}
diff --git a/net/6lowpan/nhc/core.h b/net/6lowpan/nhc/core.h
new file mode 100644
index 0000000..5613fae
--- /dev/null
+++ b/net/6lowpan/nhc/core.h
@@ -0,0 +1,122 @@
+#ifndef __6LOWPAN_NHC_H
+#define __6LOWPAN_NHC_H
+
+#include <linux/skbuff.h>
+#include <linux/rbtree.h>
+#include <linux/list.h>
+
+#include <net/6lowpan.h>
+#include <net/ipv6.h>
+
+/**
+ * LOWPAN_NHC - helper macro to generate nh id fields and lowpan_nhc struct
+ *
+ * @varname: variable name of the lowpan_nhc struct.
+ * @nhcname: const char * of common header compression name.
+ * @nexthdr: ipv6 nexthdr field for the header compression.
+ * @nhidsetup: callback to setup id and mask values.
+ * @nhidlen: len for the next header id and mask, should be always the same.
+ * @nhuncompress: callback for uncompression call.
+ * @nhcompress: callback for compression call.
+ */
+#define LOWPAN_NHC(varname, nhcname, nhnexthdr, \
+ nhidsetup, nhidlen, \
+ nhuncompress, nhcompress) \
+ static u8 name##_val[nhidlen]; \
+ static u8 name##_mask[nhidlen]; \
+ static struct lowpan_nhc varname = { \
+ .name = nhcname, \
+ .nexthdr = nhnexthdr, \
+ .id = name##_val, \
+ .idmask = name##_mask, \
+ .idlen = nhidlen, \
+ .idsetup = nhidsetup, \
+ .uncompress = nhuncompress, \
+ .compress = nhcompress, \
+ }
+
+/**
+ * struct lowpan_nhc - hold 6lowpan next hdr compression ifnformation
+ *
+ * @node: holder for the rbtree.
+ * @name: name of the specific next header compression
+ * @nexthdr: next header value of the protocol which should be compressed.
+ * @id: array for nhc id. Note this need to be in network byteorder.
+ * @mask: array for nhc id mask. Note this need to be in network byteorder.
+ * @len: the length of the next header id and mask.
+ * @setup: callback to setup fill the next header id value and mask.
+ * @compress: callback to do the header compression.
+ * @uncompress: callback to do the header uncompression.
+ */
+struct lowpan_nhc {
+ struct rb_node node;
+ const char *name;
+ const u8 nexthdr;
+ u8 *id;
+ u8 *idmask;
+ const size_t idlen;
+
+ void (*idsetup)(struct lowpan_nhc *nhc);
+ int (*uncompress)(struct sk_buff **skb);
+ int (*compress)(struct sk_buff *skb, u8 **hc_ptr);
+};
+
+/**
+ * lowpan_search_nhc_by_nhcid - returns the 6lowpan nhc by nhcid
+ *
+ * @skb: skb with skb->data which is pointed to 6lowpan nhc id.
+ */
+struct lowpan_nhc *lowpan_search_nhc_by_nhcid(const struct sk_buff *skb);
+
+/**
+ * lowpan_search_nhc_by_nexthdr - return the 6lowpan nhc by ipv6 nexthdr.
+ *
+ * @nexthdr: ipv6 nexthdr value.
+ */
+struct lowpan_nhc *lowpan_search_nhc_by_nexthdr(const u8 nexthdr);
+
+/**
+ * lowpan_add_nhc - register a next header compression to framework
+ *
+ * @nhc: nhc which should be add.
+ */
+int lowpan_add_nhc(struct lowpan_nhc *nhc);
+
+/**
+ * lowpan_del_nhc - delete a next header compression from framework
+ *
+ * @nhc: nhc which should be delete.
+ */
+void lowpan_del_nhc(struct lowpan_nhc *nhc);
+
+/**
+ * lowpan_nhc_do_compression - wrapper for calling compress callback
+ *
+ * @nhc: 6LoWPAN nhc context, get by lowpan_search_nhc_*.
+ * @skb: skb of 6LoWPAN header to read nhc and replace header.
+ * @hc_ptr: pointer for 6LoWPAN header which should increment at the end of
+ * replaced header.
+ * @iphc0: First iphc byte, to set NHC bit.
+ */
+int lowpan_nhc_do_compression(struct lowpan_nhc *nhc, struct sk_buff *skb,
+ u8 **hc_ptr, u8 *iphc0);
+
+/**
+ * lowpan_nhc_do_uncompression - wrapper for calling uncompress callback
+ *
+ * @skb: skb of 6LoWPAN header, skb->data should be pointed to nhc id value.
+ * @hdr: ipv6 header to set the according nexthdr value.
+ */
+int lowpan_nhc_do_uncompression(struct sk_buff **skb, struct ipv6hdr *hdr);
+
+/**
+ * lowpan_init_nhc - init all nhcs
+ */
+int lowpan_init_nhc(void);
+
+/**
+ * lowpan_cleanup_nhc - cleanup all registered nhcs
+ */
+void lowpan_cleanup_nhc(void);
+
+#endif /* __6LOWPAN_NHC_H */
--
2.0.3
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